1 Introduction
2 Pre-negotiation Preparation and Support
2.1 Negotiation Template Design and Evaluation
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Step 1 The negotiator evaluates the relative importance of all negotiation issues by assigning the score (weight) to each of the issues such as:where P is a pool of scoring points used for building the scoring system (usually \(P=100\) or \(P=1)\).$$\begin{aligned} \sum _{k=1}^n {w_k } =P, \end{aligned}$$(3)
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Step 2 The negotiator evaluates each option \(x_k^r \in X_k \) within each negotiation issue i by assigning a score \(u(x_k^r )\) such as:The most preferred (best) option receives the maximum score resulting from the issue weight \(w_k ,\) while the worst—the rating equal to 0.$$\begin{aligned} u\left( x_k^r\right) \in [0,w_k ], r=1,\ldots ,|X_k |, k=1,\ldots ,n. \end{aligned}$$(4)
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Step 3 The global scores of offers from X are determined as an additive aggregate of ratings of options that comprise this offer. For any offer \(a_j \in X\) the score is determined by the following formula:where \(z_k^r (a_j )\) is a binary multiplier indicating if the rth option of the kth issue was used to build the jth offer (1) or not (0).$$\begin{aligned} S(a_j)=\sum _{k=1}^n {\sum _{r=1}^{\left| {X_k } \right| } {z_k^r (a_j )\cdot u\left( x_k^r\right) ,} } \end{aligned}$$(5)
2.2 Using Negotiation Offer Scoring Systems in Actual Negotiation
Issues to negotiate | Issue options |
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Number of new songs (introduced and performed each year) | 11; 12; 13; 14 or 15 songs |
Royalties for CDs (in percent) | 1.5; 2; 2.5 or 3 % |
Contract signing bonus (in dollars) | $125,000; $150,000; $200,000 |
Number of promotional concerts (per year) | 5; 6; 7 or 8 concerts |
2.3 Problems with Using Classic SAW-Based Scoring Systems in Negotiation
3 The ZAPROS Approach in the Evaluation of the Negotiation Template
3.1 The Verbal Decision Analysis and the ZAPROS Procedure
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Step 1 Building the evaluation scale for each criterion considered in the decision-making problem (i.e., defining the options that will describe various resolution levels within each negotiation issue).
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Step 2 Comparing the ideal alternative and the hypothetical alternatives from the set \(H_{nIRS} \) pair-wisely, where \(H_{nIRS} \) is a subset of vectors from X with the best possible values for all the criteria but one, using the ordinal scale (e.g., more preferable, less preferable, and equally preferable). The DM’s comparisons have to be checked for consistency through transitivity of preferences.
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Step 3 Constructing on the basis of pairwise comparisons the JOS, which is a complete rank order of the ideal alternative and the hypothetical alternatives from \(H_{nIRS} \subset X\), each with the best evaluations for all the criteria but one (built within step 2). The JOS rank for the most preferred alternative (the Ideal Reference Vector) is 1.
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Step 4 Comparing the actual decision-making alternatives pair-wisely using the JOS and constructing a partial order on the set of them.In order to compare the alternatives the following rule is used: alternative \(a_i \) is not less preferable than alternative \(a_j \), if for each criterion value of \(a_i \) there may be found a not more preferable unique criterion value of alternative \(a_j \). The way to implement this rule is as follows: let us substitute a criterion value in each alternative by the corresponding rank from the Joint Ordinal Scale (\({ JOS}(a_i ))\), then rearrange them in the ascending order (from the most preferred to the least preferred one), so that \({ JOS}_1 (a_i )\le { JOS}_2 (a_i )\le \cdots \le { JOS}_n (a_i)\) and apply the following rule: alternative \(a_i \) is not less preferable than alternative \(a_j \), if for each \(k=1,2,\ldots ,n \quad { JOS}_k (a_i )\le { JOS}_k (a_j )\).
3.2 Example
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Step 1 It is assumed here that the negotiator prefers to evaluate options for negotiation issues using descriptive forms rather than assign the points to the issues and options like in the SAW procedure. Therefore, following the ZAPROS procedure, Fado constructs firstly the evaluation scale for the options for each negotiation issue, taking into account his subjective perception of the negotiation situation. It is worth noting that the same level in the evaluation scale may be assigned to different options. For instance, Fado can maintain that the difference between 5 and 6 concerts is irrelevant to him, and thus, these options are in his opinion equivalent. In the unpublished results of the Inspire experiments we have observed that negotiators actually assigned the same points of scores to different options, even if the available preference information suggested that there were differences between them. Table 2 presents the negotiation template with evaluation scales for options built by the negotiator. Let us observe that in the Inspire system we could actually build and evaluate (using the SAW procedure implemented to the system) \( 4\, \times \, 5 \,\times \, 4 \,\times \, 3=240\) feasible negotiation offers. The evaluation scales presented in Table 2 have limited the number of packages taken into consideration when building the scoring system to \( 3 \times 3 \times 2 \times 3=54\) only, as, for instance, the following offer: 5 concerts, 13 songs, 2.5 % royalties and 200,000$ contract bonus is worth exactly the same as the offer: 6 concerts, 15 songs, 3 % royalties and 200,000$ contract bonus.
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Step 2 The negotiator compares pair-wisely the Ideal Reference Vector [5 or 6; 14; 2.5 or 3; 200] and the hypothetical offers from the set \(H_{nIRS} \), where \(H_{nIRS}= \{[5\hbox { or }6; 14; 1.5 \hbox { or }2; 200], [5\hbox { or }6; 14; 2.5\hbox { or }3; 150]\), \([5 \hbox { or } 6; 13\hbox { or }15; 2.5\hbox { or } 3; 200], [7; 14; 2.5\hbox { or }3; 200]\), \([5\hbox { or }6; 14; 2.5\hbox { or }3; 125], [5\hbox { or } 6; 11\hbox { or }12; 2.5\hbox { or }3; 200], [8; 14; 2.5\hbox { or }3; 200]\}\). It is assumed that the negotiator is able to evaluate the options by declaring the occurrence of preferences (one alternative is better than another or they are equivalent). In order to compare the ideal offer and the offers from the set \(H_{nIRS}\) the negotiator has to answer a series of questions regarding the comparison of offers that differ in two issues only and each having only one option worse than the ones comprising the Ideal Reference Vector. For instance: “Which offer do you prefer: the offer [5 or 6; 14; 1.5 or 2; 200] with 5 or 6 concerts, 14 songs, 1.5 or 2 percent royalties and 200,000$ contract signing bonus, or the offer [8; 14; 2.5 or 3; 200] with 8 concerts, 14 songs, 2.5 or 3 percent royalties and 200,000$ contract signing bonus?”. The possible answers are as follows:Let us assume that Fado’s answer is the following: the first offer [5 or 6; 14; 1,5 or 2; 200] is better. Elicited this way and presented in Table 3, Fado’s responses are next checked for consistency through transitivity of preferences.
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the first offer [5 or 6; 14; 1.5 or 2; 200] is better (more preferable),
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the second offer [8; 14; 2.5 or 3; 200] is better (more preferable),
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these offers are equivalent (I).
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No. | Criteria (negotiation issues) | Evaluation scales (options) |
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\(\hbox {f}_{1}\)
| Number of promotional concerts (per year) | Suitable: 5 or 6 |
Neutral: 7 | ||
Unsuitable: 8 | ||
\(\hbox {f}_{2}\)
| Number of new songs (introduced and performed each year) | Favorable: 14 |
Neutral: 13 or 15 | ||
Adverse: 11 or 12 | ||
\(\hbox {f}_{3}\)
| Royalties for CDs (in percent) | High: 2.5 or 3 |
Low: 1.5 or 2 | ||
\(\hbox {f}_{4}\)
| Contract signing bonus (in thousands dollars) | Very favorable: 200 |
Favorable: 150 | ||
Not much favorable: 125 |
Hypothetical alternatives from the set \({H}_{{ nIRS}}\)
| [5 or 6; 14; 2.5 or 3; 200] | [5 or 6; 14; 1.5 or 2; 200] | [5 or 6; 14; 2.5 or 3; 150] | [5 or 6; 13 or 15; 2.5 or 3; 200] | [7; 14; 2.5 or 3; 200] | 5 or 6; 14; 2.5 or 3; 125] | [5 or 6; 11 or 12; 2.5 or 3; 200] | [8; 14; 2.5 or 3; 200] |
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[5 or 6; 14; 2.5 or 3; 200] | I | P | P | P | P | P | P | P |
[5 or 6; 14; 1.5 or 2; 200] | I | P | P | P | P | P | P | |
[5 or 6; 14; 2.5 or 3; 150] | I | P | P | P | P | P | ||
[5 or 6; 13 or 15; 2.5 or 3; 200] | I | P | P | P | P | |||
[7; 14; 2.5 or 3; 200] | I | P | P | P | ||||
[5 or 6; 14; 2.5 or 3; 125] | I | P | P | |||||
[5 or 6; 11 or 12; 2.5 or 3; 200] | I | P | ||||||
[8; 14; 2.5 or 3; 200] | I |
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Step 3 On the basis of the consistent pairwise comparisons made in step 2 the Joint Ordinal Scale (JOS) for the considered negotiation problem is built. The final result in the form of a complete rank order of the ideal offer and the offers from the set \(H_{nIRS}\) is presented in Table 4. The JOS rank for the best options for each negotiation issue (5 or 6; 14; 2.5 or 3, and 200) is equal to 1, for option 1.5 or 2 equals 2, for option 150 equals 3, etc.
Ideal vector and vectors from the set \({H}_{{ nIRS}}\)
| Evaluations | Rank in JOS |
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[5 or 6; 14; 2,5 or 3; 200] | 5 or 6; 14; 2.5 or 3; 200 | 1 |
[5 or 6; 14; 1.5 or 2; 200] | 1.5 or 2 | 2 |
[5 or 6; 14; 2.5 or 3; 150] | 150 | 3 |
[5 or 6; 13 or 15; 2.5 or 3; 200] | 13 or 15 | 4 |
[7; 14; 2.5 or 3; 200] | 7 | 5 |
[5 or 6; 14; 2.5 or 3; 125] | 125 | 6 |
[5 or 6; 11 or 12; 2.5 or 3; 200] | 11 or 12 | 7 |
[8; 14; 2.5 or 3; 200] | 8 | 8 |
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Step 4 The JOS values determined for all feasible offers within the analyzed negotiation template are presented in “Appendix”. For simplicity, we assume here that Fado is interested in the evaluation of only eight packages from the set \(A=\{a_2 ,\;a_4 ,\;a_{12} ,\;a_{19} ,\;a_{28} ,\;a_{32} ,a_{34} ,a_{40} \}\subseteq X\), where \(a_i \) is chosen from the complete list of feasible offers (see “Appendix”). The selected negotiation packages and their evaluation by means of the ZAPROS procedure are shown in Table 5.When analyzing the values contained in Table 5 it can be easily shown that, for instance, package \(a_2 \) with \(JOS(a_2 )=(1,1,1,3)\) is preferred to package \(a_4 \) with \(JOS(a_4 )=\) (1,1,1,5), as for each \(k=1,2,\ldots ,n\, JOS_k (a_2 )\le JOS_k (a_4 )\). In turn, the following packages: \(a_{12} \) and \(a_{19} \), or \(a_{12} \) and \(a_{32} \), or \(a_{34} \) and \(a_{40} \), are incomparable. In that way we are able to construct a partial order on the set of the selected offers. The relations between them are depicted in Table 6 and in Fig. 4.As we see, it turned out that some offers are incomparable (\(a_{12}\) and \(a_{19} , a_{12} \) and \(a_{32} , a_{12} \) and \(a_{34} , a_{12} \) and \(a_{40} , a_{19} \) and \(a_{32} , a_{19} \) and \(a_{40} , a_{32} \) and \(a_{34} \), and finally \(a_{34} \) and \(a_{40} )\), therefore the negotiator cannot consider, if moving from one offer to another is profitable for him or not (requires concessions or produces gains). This situation is very inconvenient for the negotiator as establishing the concession strategy is impossible.
Offer | Offer specification | Rank from JOS | JOS(\({a}_{{i}}\)) | |||
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\(\hbox {f}_{1}\)
|
\(\hbox {f}_{2}\)
|
\(\hbox {f}_{3}\)
|
\(\hbox {f}_{4}\)
| |||
\({a}_{2}\)
| [5 or 6; 14; 2.5 or 3; 150] | 1 | 1 | 1 | 3 | (1,1,1,3) |
\({a}_{4}\)
| [7; 14; 2.5 or 3; 200] | 5 | 1 | 1 | 1 | (1,1,1,5) |
\({a}_{12}\)
| [5 or 6; 13 or 15; 2.5 or 3; 125] | 1 | 4 | 1 | 6 | (1,1,4,6) |
\({a}_{19}\)
| [5 or 6; 11 or 12; 2.5 or 3; 200] | 1 | 7 | 1 | 1 | (1,1,1,7) |
\({a}_{28}\)
| [5 or 6; 14; 1.5 or 2; 200] | 1 | 1 | 2 | 1 | (1,1,1,2) |
\({a}_{32}\)
| [7; 14; 1.5 or 2; 150] | 5 | 1 | 2 | 3 | (1,2,3,5) |
\({a}_{34}\)
| [8; 14; 1.5 or 2; 200] | 8 | 1 | 2 | 1 | (1,1,2,8) |
\({a}_{40}\)
| [7; 13 or 15; 1.5 or 2; 200] | 5 | 4 | 2 | 1 | (1,2,4,5) |
Relations |
\({a}_{{i}}\)
|
\({a}_{2}\)
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\({a}_{4}\)
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\({a}_{12}\)
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\({a}_{19}\)
|
\({a}_{28}\)
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\({a}_{32}\)
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\({a}_{34}\)
|
\({a}_{40}\)
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---|---|---|---|---|---|---|---|---|---|
\(\hbox {a}_{\mathrm{i}}\)
| JOS(\(a_{i}\)) | (1,1,1,3) | (1,1,1,5) | (1,1,4,6) | (1,1,1,7) | (1,1,1,2) | (1,2,3,5) | (1,1,2,8) | (1,2,4,5) |
\({a}_{2}\)
| (1,1,1,3) | I | P | P | P | P | P | P | |
\({a}_{4}\)
| (1,1,1,5) | I | P | P | P | P | P | ||
\({a}_{12}\)
| (1,1,4,6) | I | R | R | R | R | |||
\({a}_{19}\)
| (1,1,1,7) | R | I | R | P | R | |||
\({a}_{28}\)
| (1,1,1,2) | P | P | P | P | I | P | P | P |
\({a}_{32}\)
| (1,2,3,5) | R | R | I | R | P | |||
\({a}_{34}\)
| (1,1,2,8) | R | R | I | R | ||||
\({a}_{40}\)
| (1,2,4,5) | R | R | R | I |
3.3 Discussion
4 The MACBETH Approach in the Evaluation of the Negotiation Template
4.1 The MACBETH Procedure
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Step 1 Building the evaluation scale for each criterion considered in the decision-making problem (i.e., defining the options that will describe various resolution levels within each criterion).
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Step 2 Comparing pair-wisely the differences between the importance of the criteria, as well as between the attractiveness of alternatives according to each criterion using seven semantic categories: ‘no’, ‘very weak’ (\(d_1 )\), ‘weak’ (\(d_2 )\), ‘moderate’ (\(d_3 )\), ‘strong’ (\(d_4 )\), ‘very strong’ (\(d_5 )\) and ‘extreme’ (\(d_6 )\). The description of the difference is provided in the form ‘\(d_i \) to \(d_j ',i\le j\).
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Step 3 Solving the linear programs corresponding to all the comparisons conducted, i.e., separately for the criteria and separately for the alternatives with respect to each criterion:subject to the following constraints \(S_{mac} \):$$\begin{aligned} \min v(y_1 ) \end{aligned}$$(7)$$\begin{aligned}&v({y_p })-v({y_r })=0\quad \forall y_p ,y_r \in I, \hbox { where }I\hbox { is indifference relation, } p<r,\quad \quad \end{aligned}$$(8)where \(C_{ij} \) is a preference relation,$$\begin{aligned}&d_i +0.5\le v\left( {y_p } \right) -v\left( {y_r } \right) \quad \forall i,j\in \left\{ {1,\ldots ,6} \right\} ,\, i\le j,\quad \forall y_p ,y_r \in C_{ij},\quad \quad \end{aligned}$$(9)$$\begin{aligned}&v({y_p})-v({y_r})\le d_{j+1} -0.5\quad \forall i,j\in \left\{ {1,\ldots ,5} \right\} ,\quad i\le j,\quad \forall y_p ,y_r \in C_{ij},\nonumber \\ \end{aligned}$$(10)$$\begin{aligned}&d_1 =0.5 \end{aligned}$$(11)$$\begin{aligned}&d_{i-1} +1\le d_i \quad \forall i\in \left\{ {2,\ldots ,6} \right\} , \end{aligned}$$(12)$$\begin{aligned}&v\left( {y_i } \right) \ge 0\quad \qquad \forall i\in \left\{ {1,\ldots ,n} \right\} , \end{aligned}$$(13)As a result, the optimal solution is obtained:$$\begin{aligned}&d_i \ge 0\qquad \qquad \quad \forall i\in \left\{ {1,\ldots ,6} \right\} . \end{aligned}$$(14)Solving (in order to guarantee the uniqueness of the MACBETH scales) for \(i=2\hbox { to }n-1\):$$\begin{aligned} v\left( {y_1 } \right) ,v\left( {y_2 } \right) ,\ldots ,v\left( {y_n } \right) ;\hbox { }v\left( {y_1 } \right) =\mu \left( {y_1 } \right) ,v\left( {y_n } \right) =\mu \left( {y_n } \right) =0 \end{aligned}$$(15)subject to:$$\begin{aligned}&\max v(y_i ) \end{aligned}$$(16)$$\begin{aligned}&S_{mac}\end{aligned}$$(17)obtaining the optimal solution:$$\begin{aligned}&v\left( {y_1 } \right) =\mu \left( {y_1 } \right) ,\ldots ,v\left( {y_{i-1} } \right) =\mu \left( {y_{i-1} } \right) \end{aligned}$$(18)$$\begin{aligned}&v\left( {y_1 } \right) ,v\left( {y_2 } \right) ,\ldots ,v\left( {y_n } \right) ,\hbox { where }y\max =v\left( {y_i } \right) , \end{aligned}$$(19)subject to:$$\begin{aligned}&\min v\left( {y_i } \right) \end{aligned}$$(20)$$\begin{aligned}&S_{mac}\end{aligned}$$(21)obtaining the optimal solution:$$\begin{aligned}&v\left( {y_1 } \right) =\mu \left( {y_1 } \right) ,\ldots ,v\left( {y_{i-1} } \right) =\mu \left( {y_{i-1} } \right) \end{aligned}$$(22)$$\begin{aligned}&v\left( {y_1 } \right) ,v\left( {y_2 } \right) ,\ldots ,v\left( {y_n } \right) \hbox {, where }y\min =v\left( {y_i } \right) ,\end{aligned}$$(23)Transforming the scales obtained for the alternatives and the scale constructed for the weights into 0–100 scales and assigning the scores 0 and 100 to the two end points of the scales. In the case of the criterion weights, values from the 0–100 scale should be normalized so that their sum is equal to 1.$$\begin{aligned}&\mu \left( {y_i } \right) =\frac{y\min +y\max }{2}. \end{aligned}$$(24)
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Step 4 Calculating the weighted sum of the scores of the alternatives with respect to each criterion. For any alternative \(a_j \in X\) the overall score is determined by the following formula:where \(w_k \) is a weight of kth criterion and \(u_k (a_j )\) is a partial score of the alternative \(a_j \) according to criterion \(f_k\).$$\begin{aligned} V(a_j )=\sum _{k=1}^n {w_k u_k (a_j ),} \end{aligned}$$(25)
4.2 Example
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Step 1 Negotiation issues and evaluation scales for options determined by the negotiator within the analyzed negotiation problem are presented in Table 2.
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Step 2 When using MACBETH the negotiation problem needs to be decomposed and Fado’s preferences have to be analyzed separately for the negotiation issues (in order to obtain the vector of weights) and for the salient reference options within each issue (in order to obtain partial scores for them). It is assumed that the negotiator is able not only to provide ordinal preferential information about compared elements, but also to express a qualitative judgement about the difference between their importance or attractiveness (using the seven semantic categories). Thus, Fado, instead of assigning score points to the issues and options, makes verbal comparisons between them. For instance, let us assume that his judgments regarding the relative attractiveness of the options for the issue ‘Number of promotional concerts‘ are like these presented in Table 7. As we see, Fado claims that the difference in attractiveness between 5 or 6 concerts and 7 concerts is weak, between 5 or 6 concerts and 8 concerts—strong, and between 7 concerts and 8 concerts—moderate. Pair-wise comparisons may be conducted by the negotiator using M-MACBETH software. It is worth noting that they have to be checked for consistency, but in the M-MACBETH software it is done automatically. For the analyzed negotiation problem five comparison matrices have to be built: four for comparing the options according to each negotiation issue, and the fifth one—for comparing the relative importance of the issues.
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Step 3 The matrices with pairwise comparisons made by the negotiator in step 2 as well as 0–100 scales obtained for the analyzed negotiation problem using the M-MACBETH software are presented in Fig. 5.Let us observe that building a comparison matrix in the case of the issue ‘Royalties for CDs’ is pointless. Since we compare two elements only, the better one will always obtain 100 points, and the worse one—0 points (for whatever judgement as to their relative attractiveness). Moreover, it should be emphasized that all the scores in the scales presented in Fig. 5 may be adjusted to the negotiator’s subjective opinions without violating the preferential information provided by him or her. Accordingly, if the negotiator wants to redefine the suggested score, he or she may use the value from the interval calculated by the M-MACBETH software that seems the most appropriate for him or her. In our example we assume that the scores suggested by the M-MACBETH software were accepted by the negotiator without changes. Tables 8, 9, 10, 11 and 12 present the partial scores on the 0–100 scale for the options for each negotiation issue and the one-sum weights for the issues obtained as a result of applying the MACBETH procedure.
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Step 4 The weighted sums determined for all feasible offers within the analyzed negotiation template as well as their ranking are presented in “Appendix”. In turn, eight selected negotiation packages and their evaluation by means of the MACBETH procedure are shown in Fig. 6. For instance, the overall score for option \(a_2 \) is calculated as follows:$$\begin{aligned} V(a_2 )={0.32}\cdot {100+0.32}\cdot {100+0.20}\cdot {62.5+0.16}\cdot {100=92.50} \end{aligned}$$(26)
Option | 5 or 6 | 7 | 8 |
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5 or 6 | No | Weak | Strong |
7 | No | Moderate | |
8 | No |
Resolution level | 5 or 6 | 7 | 8 |
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Value | 100.00 | 60.0 | 0.00 |
Resolution level | 14 | 13 or 15 | 11 or 12 |
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Value | 100.00 | 66.67 | 0.00 |
Resolution level | 2.5 or 3 | 1.5 or 2 |
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Value | 100.00 | 0.00 |
Resolution level | 200 | 150 | 125 |
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Value | 100.00 | 62.5 | 0.00 |
Issue | Number of promotional concerts | Number of new songs | Royalties for CDs | Contract signing bonus |
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Value | 0.32 | 0.32 | 0.20 | 0.16 |
4.3 Discussion
5 MARS—The Preference Elicitation Algorithm Based on the ZAPROS and MACBETH Methods
5.1 The MARS Procedure
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Ideal Reference Situation described by the vector with the best evaluations (resolution levels) for all criteria,
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Anti-Ideal Reference Situation expressed by the vector with the worst evaluations (resolution levels) for all criteria.
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Step 1 Determination of the evaluation scale (resolution levels) for each criterion considered in the decision-making problem.
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Step 2 Defining the Reference Situations:Building a set of hypothetical alternatives from \(H_{nIRS} \subset X\)or \(H_{nAIRS} \subset X\), where:
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Ideal Reference Vector with the best evaluations (resolution levels) for all criteria, or
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Anti-Ideal Reference Vector with the worst evaluations (resolution levels) for all criteria.
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\(H_{nIRS} \) is a set of all hypothetical alternatives with the best evaluation for all criteria but one (the set of alternatives being near to the Ideal Reference Situation),
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\(H_{nAIRS} \) is a set of all hypothetical alternatives with the worst evaluation for all criteria but one (the set of alternatives being near to the Anti-Ideal Reference Situation).
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Step 3 Pairwise comparison of the hypothetical alternatives from \(H_{nIRS} \subset X\) and the Ideal Reference Vector, or the hypothetical alternatives from \(H_{nAIRS} \subset X\) and the Anti-Ideal Reference Vector, using the ordinal scale: more preferable, less preferable, and equally preferable, or the following semantic categories: ‘no’, ‘very weak’ (\(d_1 )\), ‘weak’ (\(d_2 )\), ‘moderate’ (\(d_3 )\), ‘strong’ (\(d_4 )\) ‘very strong’ (\(d_5 )\) and ‘extreme’ (\(d_6 )\). In the latter case, the difference in attractiveness between vectors is expressed by ‘\(d_i \) to \(d_j \)’, \(i\le j\). The choice of the scale depends on DMs’ expectations, experience, and skills as well as their willingness and ability to devote adequate time and effort to conducting comparisons. Comparisons can be performed using the M-MACBETH software, which automatically verifies their consistency and offers suggestions to resolve possible inconsistencies.
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Step 4 Solution of the linear program corresponding to the comparisons performed (using the MACBETH approach and, for example, the M-MACBETH software) to obtain the scores from the 0–100 scale for the elements compared, i.e., to form the JCS—Joint Cardinal Scale:subject to the following constraints \(S_{mac} \):$$\begin{aligned} \min v(h_1 ) \end{aligned}$$(27)$$\begin{aligned}&v\left( {h_p } \right) -v\left( {h_r } \right) =0~\forall \hbox { }h_p ,h_r \in I\hbox {, }\hbox { where }I\hbox { is an indifference relation, }p<r, \nonumber \\\end{aligned}$$(28)where \(C_{ij} \) is a preference relation,$$\begin{aligned}&d_i +0.5\le v\left( {h_p } \right) -v\left( {h_r } \right) \quad \forall i,j\in \left\{ {1,\ldots ,6} \right\} ,\quad i\le j,\quad \forall h_p ,h_r \in C_{ij},\nonumber \\ \end{aligned}$$(29)$$\begin{aligned}&v\left( {h_p } \right) -v\left( {h_r } \right) \le d_{j+1} -0.5\quad \forall i,j\in \left\{ {1,\ldots ,5} \right\} ,\quad i\le j,\forall h_p ,h_r \in C_{ij}, \nonumber \\\end{aligned}$$(30)$$\begin{aligned}&d_1 =0.5 \end{aligned}$$(31)$$\begin{aligned}&d_{i-1} +1\le d_i \quad \forall i\in \left\{ {2,\ldots ,6} \right\} , \end{aligned}$$(32)$$\begin{aligned}&v\left( {h_i } \right) \ge 0\qquad \quad \forall i\in \left\{ {1,\ldots ,n} \right\} , \end{aligned}$$(33)As a result, the optimal solution is obtained:$$\begin{aligned}&d_i \ge 0\quad \qquad \quad \quad \forall i\in \left\{ {1,\ldots ,6} \right\} . \end{aligned}$$(34)Solving (in order to guarantee the uniqueness of the MACBETH scales) for \(i=2\hbox { to }n-1\):$$\begin{aligned} v\left( {h_1 } \right) ,v\left( {h_2 } \right) ,\ldots ,v\left( {h_n } \right) ;\hbox { }v\left( {h_1 } \right) =\mu \left( {h_1 } \right) ,v\left( {h_n } \right) =\mu \left( {h_n } \right) =0 \end{aligned}$$(35)subject to:$$\begin{aligned}&\max \quad v(h_i ) \end{aligned}$$(36)$$\begin{aligned}&S_{mac} \end{aligned}$$(37)obtaining the optimal solution:$$\begin{aligned}&v({h_1 })=\mu \left( {h_1 } \right) ,\ldots ,v\left( {h_{i-1} } \right) =\mu \left( {h_{i-1} } \right) \end{aligned}$$(38)$$\begin{aligned}&\quad v\left( {h_1 } \right) ,v\left( {h_2 } \right) ,\ldots ,v\left( {h_n } \right) , \hbox { where }h\max =v\left( {h_i } \right) , \end{aligned}$$(39)subject to:$$\begin{aligned}&\min v\left( {h_i } \right) \end{aligned}$$(40)$$\begin{aligned}&S_{mac} \end{aligned}$$(41)obtaining the optimal solution:$$\begin{aligned}&v\left( {h_1 } \right) =\mu \left( {h_1 } \right) ,\ldots ,v\left( {h_{i-1} } \right) =\mu \left( {h_{i-1} } \right) \end{aligned}$$(42)$$\begin{aligned}&\quad \quad v\left( {h_1 } \right) ,v\left( {h_2 } \right) ,\ldots ,v\left( {h_n } \right) , \hbox { where }h\min =v\left( {h_i } \right) , \end{aligned}$$(43)Transforming the scale obtained into 0–100 scale and assigning the scores 0 and 100 to the two end points of the scale.$$\begin{aligned}&\mu \left( {h_i } \right) =\frac{h\min +h\max }{2}. \end{aligned}$$(44)
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Step 5 Ordering the alternatives with respect to the Reference Situation, which, depending on the reference vector selected in step 2, may require one of these two following orderings:
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Ordering the alternatives with respect to the Ideal Reference Vector:Let us substitute the resolution levels in each vector describing the alternative considered in the decision-making problem by the corresponding scores from the 0–100 JCS. For each alternative the distance \(L(a_i )\)from the ideal alternative is defined by the following formula:where \({ JCS}_{ik} \) is the score from the 0–100 JCS substituting the assessment of alternative \(a_i \)according to criterion \(f_k \). The final complete ranking of the alternatives is constructed according to the distance values \(L(a_i )\) in ascending order.$$\begin{aligned} L(a_i )=\sum _{k=1}^n {(100-{ JCS}_{ik} )} , \end{aligned}$$(45)
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Ordering the alternatives with respect to the Anti-Ideal Reference Vector:Let us substitute the resolution levels in each vector describing the alternative considered in the decision-making problem by the corresponding scores from the 0–100 JCS. For each alternative the distance \(L(a_i )\) from the anti-ideal alternative is defined by the formula:where \({ JCS}_{ik} \) is the score from the 0–100 JCS substituting the assessment of alternative \(a_i \) according to criterion \(f_k \). The final complete ranking of the alternatives is constructed according to the distance values \(L(a_i )\) in descending order.$$\begin{aligned} L(a_i )=\sum _{k=1}^n {{ JCS}_{ik} } , \end{aligned}$$(46)
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5.2 Example
Ideal Reference Vector and the hypothetical alternatives from the set \({H}_{{nIRS}}\)
| Anti-Ideal Reference Vector and the hypothetical alternatives from the set \({H}_{{nAIRS}}\)
|
---|---|
[5 or 6; 14; 2.5 or 3; 200] | [8; 11 or 12; 1.5 or 2; 125] |
[5 or 6; 14; 1.5 or 2; 200] | [8; 11 or 12; 2.5 or 3; 125] |
[5 or 6; 14; 2.5 or 3; 150] | [8; 11 or 12; 1.5 or 2; 150] |
[5 or 6; 13 or 15; 2.5 or 3; 200] | [8; 13 or 15; 1.5 or 2; 125] |
[7; 14; 2.5 or 3; 200] | [7; 11 or 12; 1.5 or 2; 125] |
[5 or 6; 14; 2.5 or 3; 125] | [8; 11 or 12; 1.5 or 2; 200] |
[5 or 6; 11 or 12; 2.5 or 3; 200] | [8; 14; 1.5 or 2; 125] |
[8; 14; 2.5 or 3; 200] | [5 or 6; 11 or 12; 1.5 or 2; 125] |
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Step 1 Negotiation issues and evaluation scales for options determined by the negotiator within the analyzed negotiation problem are presented in Table 2.
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Step 2 The Ideal Reference Vector and the alternatives from the set \(H_{nIRS} \) as well as the Anti-Ideal Reference Vector and the alternatives from the set \(H_{nAIRS} \) for the considered negotiation problem look like it is presented in Table 13.
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Step 3 Let us assume that Fado wants to compare complete packages with respect to the Ideal Reference Vector and using the seven semantic categories defined in the classic MACBETH approach. The pair-wise comparisons required by the MARS procedure (made by the negotiator using the M-MACBETH software) are presented in Fig. 7. When analyzing the preferential information, it can be easily noticed that the hesitation between two or more consecutive semantic categories (except indifference) is allowed. Let us observe that it is not necessary to perform all \(s(s-1)/2\) pair-wise comparisons using the seven semantic categories, where \(s\times s-\)is a dimension of the comparison matrix, but rather focus on the minimal acceptable number of judgements equal to \(s-1\), and precisely define the preferences for all the cells placed just above the main diagonal of the matrix (see Fig. 8). All the remaining cells can be filled with the linguistic evaluation ‘positive’, which means that for the pair considered only ordinal preferential information is available. For the purpose of our example, we use the comparisons taken from Fig. 7. Note that in Fig. 7 only the hypothetical offers (each with the best resolution level for all issues but one) and the ideal offer (with the best resolution levels for all issues) are compared. According to the fundamental assumptions of ZAPROS, based on these comparisons, the basic options are ranked according to the increasing concessions their require. Applying the MACBETH’s linguistic scale allows us to assign (within step 4) cardinal score to each option, which reflects the scale of concession required, when the ideal option in the package is replaced by the option under consideration.
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Step 4 On the basis of the consistent pairwise comparisons made in step 3 the Joint Cardinal Scale (JCS) for the considered negotiation problem is built. Table 14 presents the scores on the 0–100 scale obtained as a result of applying step 4 of the MARS procedure with the help of the M-MACBETH software. Let us note that all of the scores presented in Table 14 can be adjusted to the negotiator’s opinions and beliefs without violating the preferential information provided by him or her in the matrix presented in Fig. 7. Accordingly, if the negotiator wants to redefine the suggested score, he or she is free to use the value from the interval computed by the M-MACBETH software that seems the most appropriate for him or her. In our example we assume that the scores suggested by the M-MACBETH software were accepted by the negotiator without any modification.
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Step 5 Assuming that the negotiator orders the alternatives with respect to the Ideal Reference Vector, the distance values determined for all feasible offers within the analyzed negotiation template as well as their ranking are presented in “Appendix”. In turn, eight selected negotiation packages and their evaluation by the MARS procedure are contained in Table 15. For instance, the distance value for option \(a_2 \) is calculated as follows:The final ranking of the selected offers is presented in Fig. 9. Moreover, it shows the overall scores of the offers (in brackets) and the concessions, which are necessary to make when moving from one offer to another (expressed on the arcs). Let us emphasize that all of the feasible offers from the negotiation template are fully comparable. The scores obtained within the MARS procedure provide the negotiator with all relevant cardinal data sufficient to decide which of any two packages (offers) is better and by how much. They may also be used to perform the symmetric analysis to determine the fair solution for both parties during the mediation or arbitration process or to visualize the negotiation progress and the concession paths.$$\begin{aligned} L(a_2 )=(100-100)+(100-100)+(100-100)+(100-71.43)=28.57 \end{aligned}$$(47)
Ideal Reference Vector and vectors from the set \({H}_{{nIRS}}\)
| Evaluations | Score in JCS |
---|---|---|
[5 or 6; 14; 2.5 or 3; 200] | 5 or 6; 14; 2.5 or 3; 200 | 100.00 |
[5 or 6; 14; 1.5 or 2; 200] | 1.5 or 2 | 92.86 |
[5 or 6; 14; 2.5 or 3; 150] | 150 | 71.43 |
[5 or 6; 13 or 15; 2.5 or 3; 200] | 13 or 15 | 57.14 |
[7; 14; 2.5 or 3; 200] | 7 | 42.86 |
[5 or 6; 14; 2.5 or 3; 125] | 125 | 28.57 |
[5 or 6; 11 or 12; 2.5 or 3; 200] | 11 or 12 | 14.29 |
[8; 14; 2.5 or 3; 200] | 8 | 0.00 |
Offer | Offer specification |
\(\hbox {JCS}_{\mathrm{i1}}\)
|
\(\hbox {JCS}_{\mathrm{i2}}\)
|
\(\hbox {JCS}_{\mathrm{i3}}\)
|
\(\hbox {JCS}_{\mathrm{i4}}\)
| L\(({a}_{{i}}\)) |
---|---|---|---|---|---|---|
\({a}_{28}\)
| [5 or 6; 14; 1.5 or 2; 200] | 100 | 100 | 92.86 | 100 | 7.14 |
\({a}_{2}\)
| [5 or 6; 14; 2.5 or 3; 150] | 100 | 100 | 100 | 71.43 | 28.57 |
\({a}_{4}\)
| [7; 14; 2.5 or 3; 200] | 42.86 | 100 | 100 | 100 | 57.14 |
\({a}_{19}\)
| [5 or 6; 11 or 12; 2.5 or 3; 200] | 100 | 14.29 | 100 | 100 | 85.71 |
\({a}_{32}\)
| [7; 14; 1.5 or 2; 150] | 42.86 | 100 | 92.86 | 71.43 | 92.85 |
\({a}_{34}\)
| [8; 14; 1.5 or 2; 200] | 0 | 100 | 92.86 | 100 | 107.14 |
\({a}_{40}\)
| [7; 13 or 15; 1.5 or 2; 200] | 42.86 | 57.14 | 92.86 | 100 | 107.14 |
\({a}_{12}\)
| [5 or 6; 13 or 15; 2.5 or 3; 125] | 100 | 57.14 | 100 | 28.57 | 114.29 |